1. Field of the Invention
The invention relates to an optical device for detecting organic vapor and method of using the device.
2. Description of the Prior Art
"Liquid Crystals" is an article in Aerospace Medicine, January 1969, pages 35-39 by Toliver, Roach, Roundy and Hoffman. It particularly describes liquid crystals which change color upon being exposed to organic vapors.
Also a technical bulletin by EM Chemicals on "Liquid Crystals" describes on page 7 the use of liquid crystals in gas analysis for such vapors as acetone, benzene, chloroform, petroleum ether, etc., at levels of the order of 1 ppm.
U.S. Pat. No. 3,050,982 describes a "Dew Point Measuring Apparatus" in which moisture deposited on an elongated waveguide changes the light transmitting capability of the waveguide as an indication of dewpoint. Liquid crystals are not involved.
U.S. Pat. No. 3,409,404 describes "Analytical Methods and Devices Employing Cholesteric Liquid Crystalline Materials" and relates to the detection and analysis of matter, for example, gases on a qualitative or quantitative basis. It is stated that reversible effects on liquid crystal optical properties have been observed with common organic solvents, amines, simple alcohols and organic acids . . . etc.
U.S. Pat. No. 3,704,060 describes "Electrically Controllable Light Conducting Device" and the cladding material on the waveguide can be a liquid crystal coating.
U.S. Pat. No. 3,802,760 describes "Devices for Varying Thin Film Waveguide Properties" by a "liquid crystal member" overlaying a portion of the waveguide.